![]() ![]() '\'’ cannot match any line because ‘ is not a ‘ grep -w matches a line containing only ‘ ‘ grep This option has no effect if -x is also specified.īecause the -w option can match a substring that does notīegin and end with word constituents, it differs from surrounding a Word constituent characters are letters, digits, and the underscore. Or followed by a non-word constituent character. Or preceded by a non-word constituent character. The test is that the matching substring must either Select only those lines containing matches that form whole words. Invert the sense of matching, to select non-matching lines. ![]() This option is useful for passing to shell scripts thatĪlready use -i, in order to cancel its effects because the y is an obsolete synonym that is provided for compatibility.ĭo not ignore case distinctions in patterns and input data. SHARP S) even though lowercasing the latter yields the former. Two-character string “SS” but it does not match “SS”, and it might (U 00DF, LATIN SMALL LETTER SHARP S) is normally capitalized as the Another example: the lowercase German letter “ß” This unusual character matches “S” or “s” even though uppercasing ![]() SMALL LETTER LONG S) in many locales, and it is unspecified whether Unusual lowercase counterpart “ſ” (Unicode character U 017F, LATIN ![]() Although this is straightforward when lettersĭiffer in case only via lowercase-uppercase pairs, the behavior is So that characters that differ only in case Ignore case distinctions in patterns and input data, The empty file contains zero patterns, and therefore matches nothing. When file is ‘ -’, read patterns from standard input. e ( -regexp) option, search for all patterns given. Typically patterns should be quoted when grep is used f ( -file) option, search for all patterns given. If this option is used multiple times or is combined with the Patterns separate each pattern from the next. Use patterns as one or more patterns newlines within Omit it to search only the names.Next: General Output Control, Previous: Generic Program Information, Up: Command-line Options 2.1.2 Matching Control ¶ -e patterns -regexp= patterns Omit it to show only the process ID number. For example: pgrep -af xfceĢ958 /usr/lib/x86_64-linux-gnu/xfce4/xfconf/xfconfd So, as Sergiy Kolodyazhnyy has pointed out, often neither of those ways (nor any other approach involving piping the output of ps) is really ideal and, as Nic Hartley mentioned, other ways often use pgrep. They might not even be grep commands-just commands whose names, paths, or command-line arguments contain grep. One shortcoming of those popular methods is that they'll filter out lines that contain grep even when they're not the grep command you just ran yourself. This works because is a character class that matches exactly the letter x. So another approach is to write a regular expression that matches exactly xfce but is written differently. Grep without -F treats its pattern as a regular expression rather than a fixed string. One common way to remove this distraction is to add another pipe to grep -v grep: ps x | grep xfce | grep -v grep I'm looking for information on processes that were already running when I examined what was running, not the process that's only running because of my effort to examine what is running. My grep command was shown in the output, but it's not what I'm looking for. For example, I might be looking for running programs whose names, paths, or command-line arguments suggest they're related to Xfce: ps x | grep xfceĢ958 ? S 0:00 /usr/lib/x86_64-linux-gnu/xfce4/xfconf/xfconfdģ1901 pts/1 S 0:00 grep -color=auto xfce Grep -v grep (or grep -v 'grep' or grep -v "grep") often appears on the right side of a pipe whose left side is a ps command. But in most cases where grep -v grep actually appears, this is no coincidence. See man grep for details.Īs far as the grep utility is itself concerned, it's unimportant that the pattern grep passed to it as an argument is the same as its name. Without -v, it would output only the lines in which grep does appear. Grep -v "grep" takes input line by line, and outputs only the lines in which grep does not appear. ![]()
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